1. The Field of the Invention
The present invention pertains to methods and systems for water treatment and purification and, in particular, to domestic units which are readily adaptable to treat local water in accordance with any existing long term or varying temporary condition to produce water of high purity and to a flowboard for controlling fluid distribution in the system.
2. The Prior Art
The availability of quality potable water is becoming an increasing national and world concern. There are many areas where local water has been subject to mismanagement and the quality thereof has gone down dramatically to the point that it may be dangerous for human consumption. There also are areas, such as west Texas, where natural fluorides occur at such high levels that the water will adversely affect the teeth of young children leaving them with discolored teeth for life. There are still other areas, such as the Dakotas, where the water naturally contains high levels of sulfides making the water practically undrinkable to many. Further there are periodic local and/or regional occurrences, such as the weather related natural disasters of flooding and hurricanes, when local water supplies may become contaminated and at least temporarily unsafe for drinking. Theretofore the accepted solution to these problems has been the importation of bottled water. This often is at great cost and bottled water may not always be available, such as in times of natural disasters when both water supplies and modes of transportation are damaged. Further, there is no assurance that any imported bottled water will have acceptable purity as there currently are no federal, state, or local standards in force which would have to be met by the bottlers.
Impurities in natural raw waters (surface or well water) occur in four basic different forms, namely non-ionic and undissolved impurities; ionic and dissolved impurities; gaseous impurities; and biological impurities. Each of these impurities requires separate treatment techniques and equipment for their removal.
Non-ionic and undissolved impurities include, but are not limited to, turbidity, silt, mud, suspended solids, organic matter, bacteria, oil, colloidal matter and colloidal silica. A common technique to remove such impurities is filtration using a wide variety of coarse and fine filter media. Some other techniques include coagulation, sedimentation and adsorption on activated charcoal or carbon. In raw water treatment it is customary to use a coarse filter (sand and anthracite) followed by a fine filter (cartridge), and then to treat the waiter with activated carbon to remove organic matter. In cases using pretreated water, such as municipal water supply, the first filtration with course sand is generally unnecessary.
Ionic and dissolved impurities include a wide variety of salts dissolved in water and dissociated to form positive ions, called cations, and negative ions, called anions. The major cations in natural raw water are calcium, magnesium, sodium, potassium, ammonium, iron and manganese. The major anions are carbonate, bicarbonate, hydroxide, chloride, sulfate, nitrate, phosphate, and silica. Both of these lists are intended to be representative and should not be considered in any way as all inclusive. Both the positive ions and the negative ions combine in various fashion to form a large group of compounds which would dictate the treatment process for their removal. For example, calcium and magnesium form carbonates which, in turn, cause water hardness. Water containing large amounts of carbonates must be softened to prevent fouling and clogging of equipment and other separation media.
Natural waters also include traces of different heavy metals. Several means are used to partially or completely remove such impurities. U.S. Pat. No. 5,190,659 to Wang, discussed below, is a good example of water conditioning, or partial treatment, for removal of these metals. Complete removal of metal impurities requires other techniques, such as evaporation, membrane separation and ion exchange.
Gaseous impurities include a number of gases that are soluble in water. Some are found naturally in well water, such as carbon dioxide, hydrogen sulfide, and methane. Others are the result of water purification or industrial application and include such gases as ammonia, oxygen and chlorine. In these cases, aeration, oxidation, stripping or an oxidating catalyst, such as manganese green sand zeolite, is usually a practical means for removing the dissolved gases.
Biological impurities include all types of microorganisms, bacteria, viruses, and pyrogen. Several disinfection methods are available for treating this type of impurity including boiling (limited to small volumes), chlorination, ozonation and ultraviolet radiation.
In most cases, all of these four forms of impurities coexist simultaneously and in differing amounts and their relative proportions can vary, even seasonally. No single treatment or technique is adequate for or capable of removing all impurities in one step. Multiple related or interdependent processes are normally required to rid water from such impurities.
Generally these processes must be constantly monitored to assure each form of impurity is being properly treated and removed.
Examples of known approaches to water treatment systems and apparatus are described in the following patents.
U.S. Pat. No. 4,504,389 to Rundzaitis discloses a water filter mounted on a faucet and containing therein a replaceable filter cartridge having four stages. The dwell time of water passing through this device would bring its effectiveness into question.
U.S. Pat. No. 4,876,014 to Malson describes a counter top unit for producing pure water. It utilizes a multi chamber filed with purification media (ion exchange) to purify an aqueous media, a disinfectant ultraviolet source, and means for measuring the purity of the aqueous media. No provision is made for regeneration or replacement of the purification media after exhaustion.
U.S. Pat. No. 4,894,154 to Roz discloses an individual portable water treatment device having a cartridge for filtering suspended materials, an active carbon charge, a charge of anion and cation exchange resins and a bacteria filtering cartridge.
U.S. Pat. Nos. 4,898,667, and 4,976,876, both to Diman et al, relate to point-of-use membrane filtration systems used for micro filtration, ultrafiltration or hyper filtration, depending upon the membrane pore size. The automatic control system is programmed to accomplish purge, rinse-up and sanitization procedures at predetermined intervals with predetermined combinations of procedures.
U.S. Pat. No. 5,024,766 to Mahmud has, as an objective, to maintain the purity of an ultra pure water source at a low Total Organic Carbon (TOC) and bacteria at point-of-use. A purified water source with specific resistance of 17-18 meg ohm/cm is required. The point-of-use system includes a circulation loop that contains a pump, an ultraviolet unit, a 0.2 micron filter, a twin mixed bed polisher, and an ozone generator sterilizer.
U.S. Pat. No. 5,190,659 to Wang has, as its object, to provide a point-of-entry (POE) water conditioning system. The proposed system will partially treat water contaminants. It is not intended to produce high purity water. The primary components are the vessels for filter media (a wide array of reactive and regenerative compounds are disclosed with each compound intended to treat specific problems), a process tank for regeneration and chemical circulation, a central flow control (without a description of how it works), a pump and ultraviolet units.
U.S. Pat. Nos. 5,529,689 and 5,573,666, both to Korin, describe filtration/sterilization assemblies which comprise a filtration and ultraviolet sterilization cartridge repalceably disposed within a filtration housing. The dwell time of water passing through these devices would bring their effectiveness into question.
U.S. Pat. No. 5,597,482 to Melyon describes a water purification apparatus that comprises an elongated ultraviolet lamp, for disinfecting, extending into a surrounding hollow tube. Both the lamp and tube are placed in an annulus formed of filter media disposed within a filtration housing. The dwell time for water passing through this device would give rise to questions of its effectiveness.
It is an object of the present invention to provide a method and system for point-of-use, counter top water conditioning and purification. The subject method and system are primarily intended for residential and lower volume commercial markets by improving the aesthetic quality of water and controlling, or substantially eliminating, any and all ionic and/or microbiological contamination naturally occurring in the raw water. Each unit has a flowboard which can be specially configured for the local water supply with replaceable cartridges for filtration, adsorption, reverse osmosis, ion exchange, and biological disinfection. The flowboard also allows configuration for providing additives to the water during treatment. The unit can be provided with digital instrumentation. Operational safety and ease of maintenance are key features of the present invention.